Signal device



July 7,1942.

J- R. M 'c AY SIGNALDEVICE Filed Oct. 16, 1959 4 S heets-S heet l A;ATTORNEY J- RLM cKAY SIGNALDEVICE July 7, 1942.

Filed Oct. 16, 1939 4 Sheets-Sheet 2 l\ g n NVENTOR BY 5 I l h; ATTbRNEYi ha..

July 7,1942. m. MaOKAY 2,289,315

SIGNAL DEVICE Filed Oct. 16, 1939 4 Sheets-Sheet 3 INVENTOR I I;ATTORNEY Patented July 7, 1942 cries 2,289,315 SIGNAL DEVICE John R.MacKay, West to Wallace & Tiernan Caldwell, N. 3., assignor Products,Inc., Belleville,

N. J a corporation of New Jersey Application October 16, 1939, SerialNo. 292,693

(Cl. 24o-e7.1)

19 Elaims.

This invention relates to lamp changing apparatus for automaticallyreplacing electric lamps which have failed. The invention has been mademore especially with the idea of providing an apparatus of this kind forbeacons, such as aviation and marine beacons, or other signal devicesusing comparatively high wattage lamps which are successively positionedin a fresnel type lens or other optical system of restricted dimensions.

The invention aims lamp-changing apparatus especially suitable for suchuse and which shall be of comparatively simple and rugged constructionand very reliable in operation, shall, in the most approved form, haveno relays or delicate electrical contacts or other parts liable todeterioration, shall operate to replace a failed lamp rapidly and toposition the new lamp accurately, shall effect the replacement operationsmoothly and without harmful jarring, and shall maintain the positionedlamp accurately in position regardless of vibration and inertia.

To these ends, lamp mounting and positioning means according to theinvention comprises a lamp carrier, most desirably a rotary carrier,which moves the lamp into and out of position in the optical system inan arc of a circle or other suitably curved path, and on which each lampis mounted on a support which is journalled on the carrier and which iscaused, as the lamp is moved into or out of operative position, to turnon its pivotal axis so as to maintain its lamp in an upright position.

Being maintained upright, or in. positions of constant parallelism, asthey move in their curved path to and from their operative position, thelamps require much less space horizontally in the plane of theirmovement'than is required by the lamps in lamp-changing apparatus ascommonly made, in which the lamps extend at all times during theirmovement radially, or at right angles to the surface of the, carrier,thus requiring a much larger space within the lens in which to move intheir curved path. In addition to other advantages, this has theimportant advantage especially in fresnel lens devices of largelyreducing apparatus cost, since the cost of fresnel lenses increases verygreatly as the size increases, so that it is very important to keep thesize of the lens at a minimum.

To insure that the lamps shall be accurately positioned and maintainedin position until the positioned lamp fails, the apparatus is providedwith indexing means which include a fixed indexing; abutment andabutment engaging memhere or parts on the carrier positioned withrespect to the several lamp supports.

Other objects, features and advantages of the invention will appear fromthe following description. While intended especially for aviation and toprovide an improved marine beacons having fresnel lenses and usingcomparatively high power lamps, the invention is suitable for otherlighting devices, whether of the fixed, or steady burning, light or ofthe flashing light type, and the feature of maintaining the lampsupright during their movement to and from operative position, whilefinding its greatest advantage in apparatus using lamps of comparativelyhigh Wattage because of the size and especially the length of suchlamps, is also suitable for and of advantage in apparatus using lamps ofsmaller wattage, and other motors and motor control means may, ofcourse, be used with the lamp mounting and positioning means of theinvention.

A full understanding of the invention can best be given by a detaileddescription of an apparatus embodying the various features of theinvention in the form now considered best, and of certain modificationsthereof, and such a description will now be given in connection with theaccompanying drawings, in which:

Fig. 1 is a perspective view of a lamp changing apparatus according tothe invention;

Fig. 2 is a side view of the apparatus partly in central verticalsection;

Fig. 3 is a back view of the apparatus parts shown in section;

Fig. 4 is an enlarged detail view taken on line 4-4 of Fig. 2;

Fig. 5 is an enlarged detail View taken on line 5-5 of Fig. 3;

Fig. 6 is a detail sectional view taken on line 6-5 of Fig. 2;

Fig. 7 is an enlarged detail view partly in section on line 1-! of Fig.2;

Fig. 8 is a perspective somewhat schematic view partly broken away ofthe support casting and certain parts of 'the apparatus, and showingdiagrammatically the wiring connections;

9 is a diagrammatic view showing the driving motor and electricalconnections;

Fig. 10 is a rear view, with parts omitted, showing an alternative meansfor maintaining the lamp supports in constant parallelism during themovement of the carrier; and

Figs. 11 and 12 are diagrammatic views illustrating alternative forms ofdriving motors.

Referring to the drawings, and first to Figs. 1 to 9, the various partsof the apparatus are mounted on a support casting it which has avertical front wall H and side walls 12 and I3 and a base M. A rotarylamp carrier I5 is mounted on a non-rotating stub shaft l6 which extendsforward from the support wall II, the reduced inner end of the shaftextending through the wall and being secured by a lock nut I1 and heldagainst turning, as by a pin I8. As shown, the carrier i5 is in the formof an arm which carries two lamps, one at each end at equal dis- Withtances from its pivotal axis, one of the lamps, A, being the normal, orworking, lamp and the other, B, the spare, or replacement, lamp. Acarrier mounting only two lamps is shown for simplicity, but it will beunderstood that the carrier may mount more than two lamps and will beofsuch form as is required according to the number of lamps to becarried, the only limitation to the number of lamps being the degree ofinterference that will be presented by the spare lamps intercepting theusable light rays emitted by the positioned lamp.

It will be understood that the apparatus shown is intended to be mountedin association with a fresnel lens or other optical system so that thepositioned upper lamp will be properly located within the lens or otheroptical system. In one type of aviation beacon having a fresnel lens, thpositioned lamp within the lens is reciprocated vertically atfrequencies between 20 and. 60 times per minute in order. to produce a360 cone of light of wide divergence. The lamp changing apparatus shownis especially suitable for such use, the support casting in such casebeing mounted on a vertically reciprocating support, one of the objectsof the invention being to provide an apparatus which will withstand thevibration and inertia forces resulting from such reciprocation withoutdanger of displacement of the positioned lamp with relation to the lens.

The rotary lamp carrier I is given its lamp changing movement by adriving motor 29 which together with a reduction gear unit 2| is mountedon the side wall I2 of the support. The motor, through the reductiongearing and through bevel gears 22, indicated by dotted lines in Fig. 2,and pinion 23, drives a gear 24 fast on the hub of the carrier l5. Aratchet gear 25 is fastened to the gear 24, and a pawl 26 pivoted on thefront wall ll coacts with the ratchet gear to prevent backward rotation.The pawl 26 thus serves as a detent to prevent the lamp carrier beingturned dexing means for determining the exact position of the positionedlamp and for maintaining the positioned lamp accurately in position.When to serve as the indexing detent, an eccentric carried by a stubadjustment of which the pawl may be adjusted to determine the exactposition at which the carrier is stopped to position the lamp accuratelyin the optical system.

Each lamp is carried by a support casting 30 which is rotatably mountedon a stub shaft 3| extending horizontally forward from the carrier. Eachof the stub shafts 3i is non-rotatably mounted near one end of thecarrier arm by having its inner end extend through a hole in the thelamp are secured by means of thumb screws 36. The lamp carrier l5 andthe lamp supports 30 are most desirably journalled on their shafts bymeans of bearing bushings 37 made of a suitable metal-impregnatedgraphite, as this mateand heat resistant and reother than that affordedby rial is very wear quires no lubricant the material itself.

The stationary stub shaft i 6 on which the lamp carrier arm I 5 isjournalled carries in front of the carrier arm two spaced sprocketwheels 46 and 4| which are clamped on the shouldered end of the shaft bymeans of a lock nut 42 and secured against turning on the shaft, as bymeans of a pin 43 which extends into a thrust collar integral with theshaft. Each of the lamp supports 30 has fast on its inner end a sprocket45, and these two sprockets are geared one with each of the stationarysprockets 45 and 4| by endless sprocket chains 46. The two sprockets 45and the sprockets 40 and 4| are all of the same size. When, therefore,the carrier is turned on its axis the lamp supports are by the chainsand sprockets given an angularly equal but opposite rotation, so thatthe lamp supports as they are moved by the carrier maintain a positionof constant parallelism, the lamps being thus maintained in verticalposition regardless of the an gular position of the carrier arm.

From each lamp support 30, from each socket member 35 in theconstruction shown, extend two conducting strips 53 and 5|, one of whichis electrically connected to each of the two socket contacts, and eachof these strips carries a contact 52 of suitable non-corrodingconducting material, such as silver. The upwardly facing contacts 52 ofthe positioned lamp engage downwardly facing stationary contacts 53carried by forwardly extending conducting strips 54 and 55 which aremounted on rigid fixed conducting strips 56 and 51, respectively, by ahinge connection 58 which permits limited upward movement of thecontact-carrying and 57, and by which springs the strips 54 and 55 arepressed downward to hold their contacts 53 pressed firmly against thecontacts 52 of the positioned lamp. To avoid welding due to themomentary heavy inrush of current to the cold filament of a newlypositioned lamp, the contacts 53 are made with a contact surface of asuitable non-welding material, such as the silverimpregnated graphiteknown as silver graphalloy. Obviously, the contacts 52 might be of thenon-welding material and the contacts 53 of plain silver or othersuitable metal. The lower portions of the fixed strips 56 and 5'! aresecured to the support wall ll each by two bolts 62 and 63, the stripsand bolts being insulated from the wall by panels 64 and 65 ofinsulating material. Electric connection to the contact strips 54 and 55is made through the bolts 63 to the strips 56 and 51, flexibleconductors 66 and 61 being most desirably provided between strips 54 and55 and between strips 56 and 51.

For raising the contact-carrying strips 54 and 55 to permit the contacts52 of the lamp socket member which is being moved into operativeposition to enter beneath the contacts 53, and for releasing the strips54 and 55 when the lamp has reached its operative position so that thestrips may move down under pressure of the springs 59 to press theircontacts 53 against the positioned contacts 52, the carrier arm I 5 hasat each end beyond the stub shaft 3| a cam plate 10 which engages shoes12 and 13 on the strips 54 and 55, respectively, and forces them and thestrips 54 and 55 upward as the carrier arm approaches its lamppositioning position, and then, when the lamp has reached its operativeposition releasesthe shoes abruptly. The shoes 12 and 13 then serve asindexing abutments coacting with the shoulders 14 and 15 of the cam toinsure accurate positioningof the lamp and to maintain it exactly inposition until the lamp fails, since when the cam releases the shoes andthe contacts 53 drop into engagement with the contacts 52 to completethe circuit to the positioned lamp, the driving motor as hereinafterexplained, is not only stopped suddenly but immediately rotates in thereverse direction sufficiently to move the carrier backward such shortamount. as may be permitted by the indexing abutment, that is, suchamount as will bring the cam shoulders firmly against the abutmentshoes, or such amount as will bring the indexing tooth of the ratchetwheel firmly against the pawl 26 if the pawl is serving as the indexingabutment. The carrier is thus brought to a precise definite position,and thereafter, by its tendency to rotate backward, the motor holds thecarrier in this position so long as current flows in the lamp circuit.The positioned lamp is thus accurately positioned and maintained inposition until it fails, regardless of the vibration and inertia forcesto which the apparatus is liable to be subjected. The strips 54 and 55,when the shoes 12 and 1.3 serve as indexing abutments, are horizontallyrigid, and their mounting, including their hinged connections 58, issuch that the shoes 12 and 13 are not horizontally movable and thusserve their purpose of acting as rigid abutments for the shoulders ofthe cam 1!]. Either the cam plates 1!) or the shoes 12 and 13 or theirmounting on the conducting strips 54 and 55 must, in the constructionshown, be made of suitable insulating material.

As will be understood from the foregoing description, the pawl 25, withproperly positioned teeth on the ratchet wheel 25, may serve as theindexing abutment for insuring accurate positioning of the lamp bystopping backward movement of the carrier at the proper point andthereafter holding the carrier against the continued tendency of themotor to turn it backward so long as current flows in the lamp circuit.A construction providing an indexing abutment or abutments to be engagedby coacting parts at the outer ends of the carrier arm, or otherperipheral portions of a carrier of other form has the advantage thatthe ooacting abutment-engaging parts for each lamp support may beadjustably positioned with relation to such support. To provide for suchadjustment, the cam. plates 10 are adjustable on the carrier arm in thedirection of the movement of the arm.

To provide for slight adjustment of the stub shafts 3| for adjusting thetension of the sprocket chains 46 to keep them sufficiently tight toavoid lost motion on the one hand and to keep friction at a minimum onthe other hand, the end of each of the shafts 3| which extends throughthe arm I5 is made slightly smaller than the hole in the arm and twoadjusting screws 86 and 8| are provided extending at an angle to eachother and bearing against the under side of the shaft. By adjustingthese screws when the lock nut 32 is loosened, the shaft and itssprocket may be adjusted so that when the lock nut is again tightened upthe shaft will be held rigidly in its properly adjusted position. Inorder further to reduce the possibility of undesirable movement or playof the sprocket chains on the teeth of the sprockets 45 and thestationary sprockets 4B and 4|, and thereby further to insure accuracyin the positioning of the lamp supports, the cross-pins of the chainsand the teeth of the sprockets are suitably conformed.

The driving motor 25 illustrated, and which is claimed in mycontinuation-impart application Serial No. 421,451, filed December 3,1941, is a rotary armature alternating current induction motor of theshaded pole type. As illustrated best in Fig; 9, the motor has the usualfield winding 85, and two shading coils 86 and 81 which when shortcircuited cause rotation of the mo-v tor in the direction to move thelamp carrier clockwise when viewed from the front, that is, from theleft of Fig. l and counter-clockwise when viewed from the back as inFig. 3. These shading coils are connected in a closed circuit whichincludes an impedance 90 which is also connected in the lamp circuit inseries with the positioned lamp. Rather than a non-inductive resistance,the impedance is most desirably a reactance, as indicated in Fig. 9, andthe impedance is of such value that when normal current is flowingthrough the lamp circuit there is ap-. plied to the shading coils an E.M. F. of greater value than the E. M. F. normally induced in the shadingcoils by the field winding of themotor, and the connections are suchthat this applied E. M. F. is of opposite phase from the E. M. F.induced in the coils by the field winding. This applied E. M. F. willtherefore cause the motor to rotate in a reverse direction, or backward,or to tend to rotate backward against the restraint of the detent means.When, however, no current is flowing in the lamp circuit, the presenceof the impedance in the shading coil circuit doesnot prevent normalforward rotation of the motor. By thus applying to the shading coilswhen normal current flows in the lamp circuit an E. M. F. of oppositephase from and of greater value than the E. M. F. normally induced inthe shading coils by the field winding, the necessity of providing amotor of this kind with additional and oppositely placed shading coilsto effect reverse rotation as shown in Patent No. 2,258,575 granted onmy application Serial No. 190,565 is avoided.

In Figs. 2, 3 and 5 there is shown the special variable reactance devicereferred to in the introductory part of this specification and which forreasons there pointed out is most desirably used. This variableimpedance device comprises a reactance coil 9i having comparatively fewturns of heavy insulated wire carried on a tube 92, which may be made ofinsulating material or may be a metal cylinder with a longitudinal slotto reduce eddy current losses, and within the tube is a two-part coreformed by an upper fixed part 95 and a lower part 94 which is movablewithin the tube in the manner of a solenoid core, both parts being madeof soft or laminated iron. The movable lower core member 94 has ashading coil 95 set into its upper end for holding purposes when thedevice is energized by alternating current. The device is carried by abracket 95 formed of two angle plates of soft or laminated ironconnected together and to the side wall l2 against. a panel ofinsulating material 91 by screws 55. The arm of one of these angleplates extends over and is secured to the fixed core member 83, and thearm of, the other angle plate holds the lower end of the tube 92. Thebracket thus forms a U-shaped magnetic return for the magnetic fluxcreated by the coil 9|. A spring 99 tends to draw the core member 94down away from the member 93 and against a stop plate I69, as shown inFig. 3, thus opening an air gap I III between the two core members. Thetension of the spring 99 is sufilcient to draw the core member 34 downto the position shown in Fig. 3 when only the normal shading coilcurrent induced by the motor field flows through the reactance coil QI,but not sufficient to resist the upward pull on the core member 94 whennormal lamp circuit current flows through coil SI, the core member 94then being drawn upward by magnetic action to close the air gap IIlI.

As will be understood, the air gap Nil, formed wfhen the core member 9Gis in its retracted position, increases the reluctance of the magneticcircuit formed by the U-shaped bracket 96 and the two core members 93and 94, and the reactance of the coil BI is then less than when the coremember 34 is in its upper position abutting the core member 93. When thecore member 94 is in its upper position abutting the member 93, themagnetic circuit is improved and the reluctance of the flux pathdecreased, thus increasing the reactance of the coil.

The feed line from the source of alternating current is connected tobinding posts H and III carried by a terminal panel II2 mounted on theside Wall I2. The Wiring connections are shown by Figs. 8 and 9. Currentfrom one side of the source connected to the binding post IIO flows in acircuit including wire II5, reactor coil 9|, wire I I6, connector III,and conducting strip 54, from which connection is made through contacts53 and 52 and conducting strip 56 to the positioned lamp, and from thelamp circuit is completed through conducting strip I, contacts 52 and53, conducting strip 55, wire H8 and binding post III to the other sideof the current source. The field winding of the motor 20 is, as shown,energized from the same current source, the circuit extending by wire I20 to the motor binding post strip I2I and by wire I22 to one side ofthe field winding, the other side of the field winding being connectedto the terminal post II I by wires I23 and I24 through a normally closedswitch I25 hereinafter described. Shading coils 86 and 8! of the motorare connected to binding posts on the panel I2I and connected inparallel across the reactance coil Si by wires I26 and I26. A signalswitch I30, which will be hereinafter described, is connected to bindingposts I 3| and I32 on the panel II2 by wires I33 and I34.

When a live lamp is moved into operative position, that is, in theposition of the lamp A in Fig. 1, it is connected in the lamp circuit,and the lamp circuit current then flows through the reactance coil SI,and, the core member 94 being by such flow raised to close the air gapIUI, produces a voltage drop across the coil, causing current flow inthe shading coil circuit under an E. M. F. which is greater than the E.M. F. normally induced in the shading coils by the motor field winding85 and is opposite in phase. A rotating magnetic field is thus producedby the shading coils in such direction as immediately to stop the motorand cause it to start rotating backward, that is, in the reversedirection from its normal direction of rotation. This backward rotationimmediately forces the indexing members into engagement and the tendencyof the motor to rotate backward then maintains the lamp in proper focalposition at all times against the tendency of vibration to move thecarrier and lamp out of position until the newly positioned lamp fails.On failure of the lamp, however, flow of lamp circuit current throughthe reactance coil 9| ceases, the core member 94 of the reactor isretracted, thereby re-establishing the air gap IUI and reducing theimpedance of the coil, and current induced by the motor field windingthen flows in the shading coil circuit, with the result that normalshading action takes place in the motor and the motor rotates in itsnormal forward direction, driving the lamp carrier forward, that is, inclockwise direction as viewed in Fig. 1. The motor continues to rotate,causing this forward movement of the lamp carrier, until a new lamp hasbeen moved into focal position. Immediately on the positioning of thenew lamp, there is a momentary heavy rush of current to the coldfilament of the lamp, and the flow of this heavy current through thereactance coil 9I raises the core member 94 to close the air gap andincrease the impedance of the coil, and the motor is immediately stoppedand caused to rotate in the reverse direction sufficiently to move thecarrier backward a short amount as may be permitted by the indexingmeans, thereby positively indexing the lamp; and thereafter, until thenewly positioned lamp by the tendency maintained pointed out.

The signal switch I30 mounted on the side wall I3 is a normally open,enclosed plunger-type switch operated by a face cam I 35 on the rearside of the gear 24, shown in ating plunger of the cam extending throughan opening in the support wall I I. This switch is connected, as beforestated, to binding posts on the terminal panel I I2 from which circuitconnection is made to a remotely located pilot light or other signaldevice, and the cam I35 is formed to close the switch on movement of themotor to rotate backward in accurate position, as before opening in thewall II to be operated by another face cam I36 on the rear side of gear24. This limit switch is a normally closed switch, and its cam I36 isformed to operate the switch to open the motor circuit only after bothlamp in the apparatus shown, have failed, that is,

tus were one fails, the carrier and lamp are bring the newly installedworking lamp into operative position so that the apparatus will not beleft in condition with no reserve lamp.

Fig. shows a gear train for maintaining the position of constantparallelism of the lamp supports as the carrier arm rotates, which maybe used in place of the sprockets and chains of the apparatus of Figs.1, 2 and 3. In this gear train construction, idler gears I40 and MI aremounted on the carrier arm I5, one on either side of and in engagementwith a gear I42 fast on the nonrotating stub shaft It on which thecarrier arm is journalled. The idler gear I40 engages a gear I43 fast onone of the lamp supports in place of the sprocket 45 of Figs. larly theidler gear I4l engages a gear I44 fast on the other lamp support 30 inplace of its sprocket 45. The lamp supports will thus be turned by thesegears on their stub shafts 3| in the same manner as by the sprocketchains of Figs. 1, 2 and 3 to maintain the lamps carried by the supportsalways in vertical position regardless of the angular position of thecarrier arm.

The idler gears I and MI are most desirably split gears formed of twolike gears set together flatwise against each other and rotatablytensioned for rotary movement with respect to each other, as by means ofa spring I45 connected at one end to one gear part and at the other endto a stud I45 extending through an opening in such gear part from theother gear part. By use of such tensioned split gears, which are wellknown, all play is removed from the gear train and accurate positioningof the lamps obtained.

While I consider it most advantageous to oper ate the lamp-changingmechanism by means of an alternating current driving motor operated onthe same current which supplies the lamp, and especially the motor andcircuit of Fig. 9, it is sometimes desirable to use commercialalternating current for the normal operation of high power beacons orother lighting apparatus, and to operate the same from a standby directcurrent source in the event of power system failure. This condition maybe'met by providing a motor and motor control means suitable for eitheralternating or direct current. Such a universal, or A. C.-D. C., motorand control means therefor suitable for use with the lamp-changingapparatus shown herein, and suitable also for other forms oflamp-changing apparatus, is shown diagrammatically by Fig. 11.

Fig. 11 shows a reversible universal series motor I with two fieldwindings I5I and I52. A quick-acting relay I53 is connected in the lampcircuit in series with the positioned lamp and a source of currentapplied to the binding posts I Ill and III. This relay is preferablyprovided with a shading coil indicated at I54, although a direct currenttype of relay may be used with a rectifier unit such as shown in Fig.12. When current flows in the lamp circuit, the armature I55 of therelay is maintained against its contact I55, thereby establishing a flowof current through the reverse field winding of the motor. This causesthe motor to tend to run backward and thereby to maintain the positionedlamp accurately in position as before explained. A resistor I58 is mostdesirably provided between the contact I55 and the field winding I52 toprevent overheating of the field winding and armature windings duringthe time that the tendency of the motor to rotate backward is restrainedby the detent means of the apparatus. When the positioned lamp burnsout, the relay 1, 2 and 3, and simi-\ I52 and armature I51 armature I55is released and swings out into engagement with contact I59, therebycompleting the motor circuit through the forward running field windingI5I and the armature I5I. This causes forward rotation of the motorwhereby the lamp carrier is moved to bring a new lamp into operativeposition, whereupon the relay armature is immediately drawn back intoengagement with contact I56 to stop the motor and cause it to runmomentarily in a reverse direction to properly index the lamp andthereafter to hold the lamp accurately in position. Lamp changinigapparatus equipped with this motor and control means will obviouslyoperate on either alternating or direct current.

In Fig. 12 I have shown a different form of motor suitable foroperationof the apparatus on either alternating or direct current. Themotor shown in this figure is a vibratory armature motor of the kindshown and claimed in the pending application of Charles F. Wallace andJohn R. MacKay, Serial No. 281,356, filed June 2'7, 1939, as a divisionof an application filed October 6, 1936. Motors of this type operate inonly one direction. This motor, as shown in Fig. 12, comprises anelectromagnetic motor IE5 having a vibratory armature I6 I aquick-acting relay magnet I52 provided with a shading coil I52, and acurrent-interrupting switch I53 which is controlled both by the motorarmature I6! and the relay magnet, the armature of the relay magnetserving as the movable member of the switch and being operated by themotor armature IEI to maintain the motor in operation so long as currentis supplied to the motor and the relay magnet is not energized, and therelay when energized opening the switch to prevent operation of themotor and holding the switch open so long as it is energized. Thevibratory armature IGI drives a shaft I64 by which the lamp carrier isturned through a pawl arm I55 acting on a ratchet wheel I56 on shaftI54, the pawl end of the arm I55 being pressed against the ratchet wheelby a spring I61. The relay magnet is connected in the lamp circuit inseries with the positioned lamp and thus prevents operation of the motorso long as a live lamp is in operative position, and, by releasing itsarmature when the positioned lamp fails, causes the motor to operate toposition a new lamp. This motor and its operation as the driving motorof a lamp-changing apparatus is more fully described in said Wallace andMacKay application. The motor is as described in said Wallace and MacKayapplication except that an adjustable abutment I68 is provided forlimiting the movement of the pawl end of the pawl arm I65 away from theratchet wheel, thereby preventing movement of the ratchet wheel exceptwhen the pawl arm is operated. Any possible continued movement of thelamp carrier after stopping of the motor, which might otherwise occurdue to momentum of a heavy lamp carrier, is thereby prevented, andaccurate indexing of the lamp is obtained.

In order to adapt this motor for universal operation, i. e., foroperation on alternating current as well as on direct current, a fullwave rectifier unit IIU is suitably connected as shown in the motorcircuit. This rectifier unit may be of the copper oxide disc type or ofother suitable type.

In a flashing light apparatus, that is, apparatus supplied withintermittent current resulting from the introduction of a currentinterrupter in one side of the supply line, it is desirable toprovidemeans whereby when, on failure of the positioned lamp, the carrier isfirst moved by the driving motor energized by the intermit tent current,the current interrupter is temporarily shunted to permit current to besupplied continuously to the driving motor from. the supply line until anew lamp has been moved into operative position, thereby avoiding therelatively slow lamp-changing operation that would result if the motorwere dependent on the intermittent current. Means suitable for thispurpose is shown and described in said Patent No. 2,258,575.

What is claimed is:

1. Lamp changing apparatus, comprising a rotary lamp carrier, aplurality of lamp supports pivotally mounted on the carrier at equaldistances from the pivotal axis of the carrier, means for rotating thecarrier and means for causing during rotation of the to position a newlamp,

carrier an angularly equal but opposite rotation of the lamp supports ontheir own pivotal axes.

2. Lamp changing apparatus, comprising a rotary lamp carrier, aplurality of lamp supports pivotally mounted on the carrier at equaldistances from the pivotal axis of the carrier, means for rotating thecarrier to position a new lamp, a stationary control member whose axiscoincides with the pivotal axis of the carrier, and connections betweensaid control member and each of the lamp supports whereby duringrotation of the carrier the lamp supports are given an angularly equalbut opposite rotation on their own pivotal axes.

3. Lamp changing apparatus, comprising a rotary lamp carrier, aplurality of lamp supports pivotally mounted on the carrier at equaldistances from the pivotal axis of the carrier and means for rotatingthe carrier to position a new lamp, the lamp supports each having gearwheels fast thereon geared to a stationary gear wheel whose axiscoincides with the pivotal axis of the carrier whereby during rotationof the carrier the lamp supports are given an angularly equal butopposite rotation on their own pivotal axes.

4. Lamp changing apparatus, comprising a rotary lamp carrier, aplurality of lamp supports pivotally mounted on the carrier at equaldistances from the pivotal axis of the carrier, means for rotating thecarrier to position a new lamp, and means for causing during rotation ofthe carrier an angularly equal but opposite rotation of the lampsupports on their own said means comprising for each lamp support asprocket wheel fast thereon, a stationary sprocket wheel whose axiscoincides with the pivotal axis of the carrier, and a sprocket chainrunning on said wheels.

5. Lamp changing apparatus, comprising a rotary lamp carrier, aplurality of lamp supports pivotally mounted on the carrier at equaldistances from the pivotal axis of the carrier, means for rotating thecarrier to position a new lamp, and means for causing during rotation ofthe carrier an angularly equal but opposite rotation of the lampsupports on their own pivotal axes, said means comprising for each lampsupport a gear wheel fast on the lamp support, and an intermediate gearwheel mounted on the carrier in engagement with a stationary gear wheelwhose axis coincides with the pivotal axis of the carrier.

6. Lamp changing apparatus, comprising a rotary lamp carrier, aplurality of lamp supports pivotally mounted on the carrier at equaldistances from the pivotal axis of the carrier, means for rotating thecarrierto position a new lamp, and means for causing during rotation ofthe carrier an angularly equal but opposite rotation of the lampsupports on their own pivotal axes, said means comprising for each lampsupport a axis coincides with the pivotal axis of the carrier, theintermediate gear for each lamp support being a split gear provided withmeans tending to cause relative rotary movement of the two gear parts.

7. Lamp changing apparatus, comprising a rotary lamp carrier, aplurality of lamp supports mounted on the carrier, each lamp supportbeing carrier parallel to the pivotal axis of the carrier, means forrotating the carrier to position a new lamp, a sprocket chain and wheelconnection between each lamp support and a stationary member whose aXiscoincides with the piveach of said stub shafts being adjustable foradjusting the tension of the sprocket.

8. Lamp changing apparatus, comprising a rotary lamp carrier, aplurality of lamp supports pivotally mounted on the carrier at equaldisto engage the contact terminal of the positioned lamp sup-port, andmeans for moving said stationary contact terminal out of engagingposition when a lamp is approaching operative position.

9. Lamp changing apparatus, comprising a rotary lamp carrier, aplurality of lamp supports pivotally mounted on the axis of the carrier,means for rotating the carrier to position a new means for causingduring rotation of the carrier an angularly equal but opposite rotationof the lamp supports on their own pivotal axes, two contact terminalscarried by each lamp support, two stationary contact terminalspositioned to engage the two contact terminals of the powhen a lamp isapproaching operative position.

10. Lamp changing apparatus, comprising a rotary lamp carrier, aplurality of lamp supports pivotally mounted on the carrier at equaldistances from the pivotal axis of the carrier, means for rotating thecarrier to position a new lamp, means for causing during rotation of thecarrier an angularly equal but opposite rotation of the lamp supports ontheir own pivotal axes, two contact terminals carried by each lampsupport, two stationary contact terminals positioned to engage the twocontact terminals of the positioned lamp support, said stationarycontact terminals being carried each by a contact arm tensioned to presssaid contact terminals against the contact terminals of the support, acam member on the carrier adjacent each lamp support for moving saidcontact-carrying arms to move their contact terminals out of engagingposition when a lamp is approaching operative position.

11. Lamp changing apparatus, comprising a rotary lamp carrier, aplurality of lamp supports pivotally mounted on the carrier at equaldistances from the pivotal axis of the carrier, means for rotating thecarrier to position a new lamp, means for causing during rotation of thecarrier an angularly equal but opposite rotation of the lamp supports ontheir own pivotal axes, two contact terminals carried by each lampsupport, two stationary contact terminals positioned to engage the twocontact terminals of the positioned lamp support, said stationarycontact terminals being carried each by a contact arm tensioned to presssaid contact terminals against the contact terminals of the positionedlamp support, a cam member on the carrier adjacent each lamp support formoving said contact-carrying arms to move their contact terminals out ofengaging position when a lamp is approaching operative position, saidcam being shouldered to serve in coaction with said contact-carryingarms as indexing means for determining accurately the operative positionof the lamp.

12. Lamp-changing apparatus, comprising a lamp carrier, a plurality oflamp supports mounted on the carrier, said carrier being movable forpositioning the lamps successively, a lamp circuit having terminals forconnecting the positioned lamp in the circuit, an indexing abutment, aplurality of abutment-engaging memhere on the carrier one adjacent toeach lamp support for co-acting with said abutment, motor means formoving the carrier forward on failure of the positioned lamp to positionanother lamp, and means for causing the motor means to urge the carrierbackward when normal current flows in the lamp circuit, whereby when anew lamp is positioned its abutmentengaging member is forced back intoengagement with the indexing abutment to accurately position the lampand is thereafter held in such engagement to maintain the lamp inposition.

13. Lamp-changing apparatus, comprising a lamp carrier, a plurality oflamp supports mounted on the carrier, said carrier being movable forpositioning the lamps successively, a lamp circuit having terminals forconnecting the positioned lamp in the circuit, an indexing abutment, aplurality of abutment engaging members on the carrier one adjacent toeach lamp support for co-acting with said abutment, said members beingindependently adjustable, motor means for moving the carrier forward onfailure of the positioned lamp to position another lamp, and means forcausing the motor means to urge the carrier backward when normal currentflows in the lamp circuit, whereby when a new lamp is positioned itsabutment-engaging member is forced back into engagement with theindexing abutment to accurately position the lamp and is thereafter heldin such engagement to maintain the lamp in position.

14:. Lamp-changing apparatus, comprising a carrier for a plurality oflamps movable for positioning the lamps successively, a lamp circuithaving terminals for connecting the positioned lamp in the circuit, anindexing abutment, an abutment-engaging member moving with the carrier,motor means for moving the carrier forward on failure of the positionedlamp to position another lamp, and means for causing the motor means tourge the carrier backward when normal current flows in the lamp circuit,whereby when a new lamp is positioned the abutment-engaging member isforced back into engagement with the indexing abutment to accuratelyposition the lamp and is thereafter held in such engagement to maintainthe lamp in position.

15. Lamp-changing apparatus, comprising a rotary lamp carrier, aplurality of lamp supports pivotally mounted on the carrier at equaldistances from the pivotal axis of the carrier, electric motor means forrotating the carrier on failure of the positioned lamp to positionanother lamp, means for causing during rotation of the carrier anangularly equal but opposite rotation of the lamp supports on their ownpivotal axes, and a limit switch for opening the motor circuit toprevent continued operation of the motor after failure of the last lampon the carrier.

16. Lamp-changing apparatus, comprising a rotary lamp carrier, aplurality of lamp supports pivotally mounted on the carrier at equaldistances from the pivotal axis of the carrier, electric motor means forrotating the carrier on failure of the positioned lamp to positionanother lamp, means for causing during rotation of the carrier anangularly equal but opposite rotation of the lamp supports on their ownpivotal axes, a normally open switch in said circuit, and means forclosing said switch on movement of the carrier following the failure ofa positioned lamp.

17. Lamp-changing apparatus, comprising a rotary lamp carrier, aplurality of lamp supports pivotally mounted on the carrier at equaldistances from the pivotal axis of the carrier, electric motor means forrotating the carrier on failure of the positioned lamp to positionanother lamp, means for causing during rotation of the carrier anangularly equal but opposite rotation of the lamp supports on their ownpivotal axes, a normally open switch in said circuit, and means forclosing said switch when the carrier moves to position the last lamp.

18. Lamp-changing apparatus, comprising a plurality of lamp supports,means for moving the lamp supports successively in a curved path to andfrom operative position, means for maintaining the lamp supports inparallelism as they are moved into and out of operative position wherebythe lamps during such movement are maintained in vertical position, acontact terminal carried by each lamp support, a stationary contactterminal positioned to engage said contact terminal of the positionedlamp support, and means for moving said stationary contact terminal outof, engaging position when a lamp is approaching operative position.

19. Lamp-changing apparatus, comprising a plurality of lamp supports,means for moving the lamp supports successively in a curved path to andfrom operative position, means for maintaining the lamp supports inparallelism as they are moved into and out of operative position wherebythe lamps during such movement are maintained in vertical position, twocontact terminals carried by each lamp support, two stationary contactterminals positioned to engage the two contact terminals of thepositioned lamp support and under tension to press thereagainst, andmeans on the carrier adjacent each lamp support for moving saidstationary contact terminals out of engaging position when a lamp isapproaching operative position.

JOHN R. MACKAY.

